1. Field of the Invention
The present invention relates generally to high track density, flexible media storage applications, and more specifically, but not exclusively, to a method and apparatus for increasing the capacity of magnetic media storage. More specifically, the present invention provides an improved two-sided magnetic tape.
2. Background of the Invention
Magnetic tape continues to be a popular medium for recording and storing information. For example, magnetic tape storage systems may hold vast quantities of data at a relatively low cost per bit stored. Magnetic tapes are easily manipulated by automated storage systems. Data may be added to information already stored on a magnetic tape. In addition, magnetic tapes may be erased and rerecorded. Furthermore, magnetic tape has a relatively long shelf life under proper storage conditions.
Magnetic tape and tape storage systems may be made increasingly more efficient and cost-effective by increasing the data storage density. Traditionally, increases in storage density have resulted from narrower data tracks, increases in the number of data tracks per tape width, increases in the density of data recorded along the length of each track, etc. These increases have resulted from improvements in the magnetic media, tape thickness, read and record electronics, tape head positioning, data encoding and decoding schemes, etc. However, all of these improvements have focused on the traditional tape configuration of a supportive web coated with magnetic material on one side.
A doubling of information density can be achieved if both sides of the supporting web are coated with magnetic material for recording and retrieving information. However, such two-sided magnetic tape schemes have been considered to be impractical for a number of reasons. For example, one problem with two-sided magnetic tape is related to a phenomenon called “print-through,” in which the data written on the media located on one side of the magnetic tape affects the magnetization of the media located on the other side. A related problem is called “contact recording” that can occur when the magnetic tape is spooled up on a reel. In this case, the two sides of the tape are in close proximity or physically touching when the tape is stored, which can cause errant magnetization of the media on either side. The use of a thicker media can help to reduce print-through and/or contact recording, but a thicker media also reduces the volumetric storage capacity of the magnetic tape.
Another problem with two-sided magnetic tape arises during tape spooling operations. Tape pack winding issues can arise with two-sided magnetic tape, because the surface(s) of one or both sides of the tape may be too smooth or too rough. For example, when relatively smooth two-sided magnetic tape is spooled at speed (e.g., with air entrainment), tape slippage (resulting from the relative smoothness of both sides) can cause such problems as stagger wraps, tape edge damage, etc. The use of a rougher surface on one side of the tape can mitigate such problems. Having too rough a surface on one side of a tape typically precludes the use of high-density recording on the magnetic media of the other side due to mechanical imprint/embossing.
Therefore, it would be advantageous to provide an improved two-sided magnetic tape that can increase storage capacity and also mitigate tape pack winding and similar problems.